Stent and Securely-Installed Artificial Valve Replacement Device Having Same

ABSTRACT

A stent and a securely-installed artificial valve replacement device having the same, the stent being of a cylindrical structure; the top of the stent is provided with a fixed ear ( 60 ); the fixed ear ( 60 ) has a neck portion ( 601 ) connected to the top of the stent, and a head portion ( 602 ) engaged with the fixed head of the stent; the head portion ( 602 ) has a bending structure for improving the overall radial thickness; and the artificial valve replacement device is comprised of a stent and a prosthetic valve fixed on the stent. The stent with a bending structure overcomes the problem of easily disengaging from the fixed head of the stent, while not affecting the release of the stent.

FIELD OF THE INVENTION

The present application relates to the technical field of medicalapparatuses, and more particularly to a stent and a securely-installedartificial valve replacement device having same.

BACKGROUND OF THE INVENTION

When a patient's own heart valves (the mitral valve, the tricuspidvalve, the aortic valve, or the pulmonary valve) mutate due tocongenital or acquired diseases and hence the valves are unable to openand close normally, health and even life may be adversely affected. Themutations of the heart valves include opening incompletely and closingincompletely, both the two situations may result in increase of cardiacload, and whether the heart can normally work under the increasing loadis a main basis that determines whether the human body heart valves needto be replaced.

Implantation of artificial heart valves by interventional operationscauses small traumas to human bodies and has a low invasion degree, andthus it is applied more and more widely. This operation can form a smallincision with a diameter of several millimeters on the skin of a patienton the premise of no use of scalpel, through the incision thevasculature system of a human body can be accessed and a transportchannel can be established, and an artificial heart valve (i.e., astent) can be transported by a special transport system to the heart andreplace a defective human body valve.

An artificial heart valve replacement device in the prior art generallyincludes a mesh stent made of memory metal material and a clover-shapedvalve that is sewed in the stent and can be opened unidirectionally,referring to FIG. 1, the stent includes three parts, which are an aorticstent 1, a valve stent 2, and a right ventricular inflow tract stent 3,and at least one T-shaped fixed ear 10 is arranged at a top edge of thestent.

In an operation, an artificial valve replacement device is transportedto an implantation point by a transport system. The transport systemfixes the artificial valve replacement device on a stent fixing head, afront end of the stent fixing head is provided with a streamline guidinghead, a core tube extends through the stent fixing head and is connectedwith the guiding head, and the core tube, the stent fixing head, and theguiding head cooperatively form a sheath core. When implanting theartificial valve, the artificial valve replacement device is positionedto engage with the stent fixing head of the transport system, a sheathtube is sheathed on the outside of the sheath core, and the stent iskept in a compressed status; the sheath tube and the sheath corecarrying the artificial valve replacement device is transported from aninlet of a blood vessel to a location of a diseased valve, and theartificial valve replacement device is then released; the stent willexpand under the action of the body temperature and push leaves of theartificial valve towards the wall of the blood vessel to complete thepositioning, afterwards, the sheath tube and the sheath core are drawnout

Before the artificial valve replacement device is released, it must bemounted in the transport system stably. If the artificial valvereplacement device is accidentally released, the life safety of thepatient will be seriously threatened.

In the transport system, the artificial valve replacement device isfixedly mounted on the stent fixing head. FIG. 2 shows a structure of aconventional stent fixing head, wherein an outer wall of the stentfixing head defines a positioning groove 11. When mounting theartificial valve replacement device, the fixed ear 10 of the stent ofthe artificial valve replacement device is fittingly embedded in thepositioning groove 11. In the prior art, a thickness of the fixed ear ofthe stent is generally about 0.4 mm, correspondingly, a depth of thepositioning groove is also about 0.4 mm, that is, the depth is verysmall. Since there is a clearance with a width of about 0.1-0.2 mmbetween the stent fixing head and the inner wall of the sheath tube, andthe transport system needs to pass the tortuous and complex vasculaturesystem to transport the artificial valve replacement device to theimplantation point, when the transport system turns, the sheath tube isbent and deformed, and thus the stent fixed ear is prone to slide outalong the clearance, resulting in disengagement of the artificial valvereplacement device.

Furthermore, in order to guide the fixed ear of the stent to enter thepositioning groove successfully and facilitate the release of theartificial valve replacement device in the operating process, as shownin FIG. 3, an opening part of the positioning groove is provided with achamfer 12, and a peripheral edge of the positioning groove is alsoprovided with a chamfer 13, however, the chamfers are easier to causedisengagement of the artificial valve replacement device.

When not being used, the stent of the artificial valve replacementdevice is in a folded state, and is a compact tubular structurefabricated by machining memory metal or shape memory alloy using lasercutting. After the stent expands in a human body, it will be in tightcontact with a blood vessel wall. If a thickness of the stent increases,not only does the processing difficulty increase, but also thecompliance and expanding performance of the stent are affected.

SUMMARY OF THE INVENTION

The present application provides a stent, which can be stably mounted ona transport system and does not affect the normal use of the stent.

A stent, wherein the stent is a cylindrical structure, a top edge of thestent is provided with at least one fixed ear, each fixed ear includes aneck portion connected to the top edge of the stent and a head portionengaging with a stent fixing head, and the head portion is provided witha bent structure configured for increasing an overall radial thicknessof the stent.

If not specially described, the term “radial direction” of the presentapplication refers to a radial direction of the stent. Since the stentis a cylindrical structure, the radial thickness refers to a thicknessof the head portion along a radial direction of the stent.

The whole head portion or a part of the head portion can be the bentstructure. After adopting the bent structure, an overall thickness ofthe head portion will increase; preferably, a ratio of a radialthickness of the bent structure to a radial thickness of the neckportion is 1.2˜3:1.

A radial thickness of the neck portion can be regarded as an overallthickness of a fixed ear without any bent structure in the prior art.When the head portion is bent, compared with the neck portion, itsthickness increases and can provide an anti-disengagement function.

An outer wall of the stent fixing head is provided with a positioninggroove, when mounting the stent, the head portion of the fixed earengages within the positioning groove, and the outside of the stent issurrounded by the sheath tube of the stent. A clearance fit is formedbetween the sheath tube of the stent and the stent fixing head; if theclearance is too large (e.g., large than 0.1 mm), since the sheath tubeof the stent is made of thin-walled polymer material, when it issubjected to a radial compression force from the head portion of thefixed ear, it will generate a flexible deformation, such that theclearance between the sheath tube of the stent and the stent fixing headwill increase several times at a part of the stent fixing headcontacting the fixed ear, thereby resulting in that the fixed eardisengages from the positioning groove; on the contrary, if theclearance is too small, it will be caused that an excessive axialresistance is generated when the stent is carried and released, therebyresulting in operating difficulty of the operation. Therefore, therequirement for the matching accuracy between the stent fixing head andthe sheath tube of the stent has become a main problem in the prior art.The present application adopts the bent structure of the head portion ofthe fixed ear to increase the radial thickness of the head portion, sothat the radial thickness of the head portion equals several times ofthe width of the clearance. Therefore, the requirement for the accuracyof the clearance can be significantly reduced, and it can be reliablyensured that the stent fixed ear will not separate from the stent fixinghead even though the axial resistance is not increased, so that thestent can be stably mounted in the transport system.

Furthermore, the bent structure is formed by re-machining the stent atwhich laser engraving has been completed, and thus does not affectbiological performance of the stent.

There are many types of bent structures. When the whole head portion isa bent structure, as one choice, the head portion is substantiallyarc-shaped, and a concave portion of the arc shape is positioned towardsan axis of the stent.

Here, a thickness of the head portion refers to a difference between aradial height of a middle portion of the arc shape and a radial heightof either end of the arc shape.

As another choice, the head portion is substantially wave-shaped.

Here, a thickness of the head portion refers to a difference between aradial height of any wave peak and a radial height of any wave trough.

The wave-shaped head portion should have at least two wave peaks.

Preferably, the wave peaks and the wave troughs of the wave-shaped headportion are alternately arranged along a circumference of the stent.

In order to embed the fixed ear in the positioning groove of the stentfixing head more stably, two ends of the head portion that abut a bottomof the positioning groove are wave troughs of the head portion.

When a part of the head portion is a bent structure, as a choice, twoside edges of the head portion are bent towards each other.

When being bent, two side edges of the head portion can be bent towardsthe same side, and can also be bent towards two opposite sidesrespectively.

A bent angle of each of the two side edges is usually at 160-180degrees, and preferably, at 180 degrees. When the bent angles of the twoside edges are at 180 degrees, a radial thickness of the fixed earequals two times of a radial thickness of the fixed ear before beingbent.

As another choice, a top edge of the head portion is bent towards theneck portion.

A bent angle of the top edge is usually at 160-180 degrees, andpreferably, at 180 degrees. When the bent angle is at 180 degrees, aradial thickness of the bent fixed ear equals two times of a radialthickness of the fixed ear before being bent.

In order to facilitate the machining of the bent structures, preferably,the fixed ear is T-shaped, and a top end of the neck portion of thefixed ear is connected with a center of a bottom of the head portion.

There can be a plurality of fixed ears arranged on a top edge of thestent evenly. Preferably, the number of the fixed ears is 2-4.

Preferably, the projection locations of the top edges of the pluralityof fixed ears on an axis of the stent are arranged to be staggered. Thatis, heights of the top edges of the plurality of fixed ears aredifferent, and in particular, heights of the top edges of every twofixed ears differ from each other. Therefore, when the stent is fixedonto the transport system, the plurality of fixed ears can be positionedsequentially; for example, a fixed ear having the highest top edge canbe positioned at first, and all other fixed ears can be positionedsequentially, wherein each fixed ear having a higher top edge ispositioned prior to each fixed ear having a lower top edge, so that theoperation is more convenient.

The present application further provides a stably-mounted artificialvalve replacement device, which comprises the above-described stent anda prosthesis valve fixed on the stent.

The prosthesis valve can be a prosthesis tricuspid valve, a prosthesispulmonary valve, a prosthesis aortic valve, and so on.

The prosthesis valve can be sewed on an inner wall of the stent, and canalso be fixed by other conventional methods.

By the arrangement of the bending structure(s), the stent of the presentapplication overcomes the problem that the stent is prone to disengagefrom the stent fixing head, the stent can be stably mounted on thetransport system, so that the safety is higher; moreover, the release ofthe stent is not affected.

The stent of the present application is designed and improved on thebasis of conventional stents, therefore, it is simple, convenient, andeasy to operate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structural schematic view of a stent of an artificial valvereplacement device in the prior art;

FIG. 2 is a structural schematic view of a stent fixing head in theprior art;

FIG. 3 is a cut-away view of the stent fixing head shown in FIG. 2;

FIG. 4 is a structural schematic view of a stent of an artificial valvereplacement device of the present application;

FIG. 5 is a structural schematic view of a first type of fixed ear ofFIG. 4;

FIG. 6 is a schematic view of mounting the fixed ear shown in FIG. 5onto a transport system (according to a first fitting method);

FIG. 7 is a schematic view of mounting the fixed ear shown in FIG. 5onto a transport system (according to a second fitting method);

FIG. 8 is a structural schematic view of a second type of fixed ear ofFIG. 4;

FIG. 9 is a schematic view of mounting the fixed ear shown in FIG. 8onto a transport system (according to a first fitting method);

FIG. 10 is a schematic view of mounting the fixed ear shown in FIG. 8onto a transport system (according to a second fitting method);

FIG. 11 is a structural schematic view of a third type of fixed ear ofFIG. 4;

FIG. 12 is a structural schematic view of a fourth type of fixed ear ofFIG. 4;

FIG. 13 is a schematic view of opening the stent of the artificial valvereplacement device of the present application before the stent isreleased.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present application will be further described hereafter withreference to the accompany drawings and embodiments.

An artificial valve replacement device of the present applicationcomprises a stent and a prosthesis valve fixed on the stent.

Taking an aortic stent as an example, a structure of the artificialvalve replacement device of the present application will be describedhereafter. However, it should be noted that the artificial valvereplacement device of the present application is not limited to use theaortic stent, but can also use a pulmonary stent, a tricuspid valvestent, etc.

As shown in FIG. 4, the stent (aortic stent) is a netlike cylindricalstructure, which comprises an aortic stent 4, a valve stent 5, and aninflow tract stent 6 that are connected sequentially.

The stent comprises a plurality of diamond unit meshes arrangedcontinuously, and three hollow areas are arranged at a side wall of thevalve stent 5. Due to the limit of the view angle, only two hollow areas9 a, 9 b of the three hollow areas are visible in FIG. 4. The hollowareas are used to respectively accommodate a top end of a prosthesisvalve when the prosthesis valve is opened. Each hollow area is formed bycombining four adjacent diamond unit meshes together, that is, at leasta part of the skeletons inside the hollow area are removed to form thehollow area. In this way, the stent is not only easy to process but alsoable to achieve a good overall strength.

Of course, the shapes of the mesh structures of the stent are notlimited to diamond, and can also be regular or irregular oval, round,rectangular, and so on, as long as they can meet the requirement forsupporting force and compliance of the stent.

A top edge of the aortic stent 4 is provided with at least one fixed ear60, which is configured to engage within a positioning groove of a stentfixing head of a transport system when the stent is implanted into ahuman body.

The fixed ear 60 is substantially T-shaped, in particular, the fixed ear60 includes a neck portion 601 and a head portion 602, the neck portion601 is connected with the top edge of the aortic stent 4, and the headportion 602 engages with a stent fixing head; a top end of the neckportion 601 of the fixed ear 60 is connected with a center of a bottomof the head portion 602, and the head portion 602 further comprises abent structure that increases an overall radial thickness of the headportion 602.

FIG. 5 illustrates a first embodiment of the bent structure of the headportion 602 of the fixed ear 60 of the present application. In thisembodiment, the whole head portion 602 of the fixed ear is bent to bearc-shaped, and a concave portion of the arc shape is positioned towardsan axis of the stent. In this way, an overall radial thickness H of thehead portion 602 (i.e., a difference between a height of a middleportion of the arc shape and a height of either end of the arc shape) isincreased. When the fixed ear 60 engages with a positioning groove, asshown in FIG. 7, a depth of a positioning groove 8 of a stent fixinghead 7 can be increased appropriately (however, it is also possible thatthe depth is not increased), so that the head portion 602 of the fixedear 60 is in tight contact with an inner wall of a sheath tube 14. Ofcourse, when the depth of the positioning groove 8 is increased, thedepth can be fit for the thickness of the head portion 602 of the fixedear 60, as shown in FIG. 6; in this way, even though the sheath tube 14is bent and/or deformed, the fixed ear 60 is not prone to disengage fromthe positioning groove 8, and thus the stent is prevented fromdisengagement.

Even though the depth of the positioning groove 8 is unchanged, sincethe overall radial thickness of the head portion 602 is increased sothat the radial thickness equals several times of a width of a clearancebetween the sheath tube 14 and the stent fixing head 7, requirement forthe accuracy of the clearance can still be greatly reduced, andrequirement for the accuracy of the sheath tube can also be reduced atan order of magnitude, such that the processing technology is simplerand easier to perform.

FIG. 8 illustrates a second embodiment of the bent structure, whereinthe head portion 602 of the fixed ear 60 is substantially wave-shaped,and wave peaks and wave troughs of the wave-shaped head portion 602 arealternately arranged along a circumference of the stent. In particular,two ends of the head portion 602 that abut a bottom of the positioninggroove 8 are wave troughs of the head portion 602, so that the fixed ear60 can be embedded in the positioning groove 8 of the stent fixing head7 more stably. FIG. 9 and FIG. 10 show mounted states of the headportion 602 of the wave-shaped fixed ear 60 in the transport system whenmounting the stent.

In a third embodiment of the bent structure of the head portion 602, thehead portion 602 of the fixed ear 60 is partially bent, in particular,two side edges of the head portion 602 are bent towards each other. Asshown in FIG. 11, the two side edges of the head portion 602 are benttowards the same side, the bent angle of each side edge equals 180degrees, and a thickness of the bent fixed ear 60 equals two times of athickness of the fixed ear 60 before being bent.

Of course, the two side edges of the head portion 602 can also be benttowards two opposite sides respectively, so that the head portion 602 issubstantially S-shaped.

FIG. 12 illustrates a fourth embodiment of the bent structure of thehead portion 602 of the present application. In this embodiment, the topedge of the head portion 602 is bent towards the neck portion 601, thebent angle equals 180 degrees, and a thickness of the bent fixed ear 60equals two times of a thickness of the fixed ear 60 before being bent;of course, a bent angle in the range of about 160˜180 degrees can alsoachieve good effect.

Obviously, when the fixed ear 60 shown in FIG. 11 or FIG. 12 engageswith the positioning groove 8, the aforementioned engaging ways (e.g.,the first engaging way) can also be adopted, and these engaging ways donot need to be repeatedly detailed here.

It should be noted that the bent structure of the head portion 602 ofthe fixed ear 60 of the present application is not limited to theabove-described embodiments but can have many variations. For example,each of the two side edges of the head portion 602 of the fixed ear 60shown in FIG. 11 is bent only once, actually, each of the two side edgescan be bent twice or more times, so that a thickness of the bent fixedear 60 with the multilayer laminate structure equals three or more timesof a thickness of the fixed ear 60 before being bent.

Furthermore, in the bent structure, the bending or curving angle of thehead portion 602 can be adjusted according to actual situations.

The number of the fixed ears 60 is usually three, as shown in FIG. 13,three fixed ears 60 a, 60 b, and 60 c are provided. Heights of top edgesof three fixed ears 60 a, 60 b, and 60 c are different, for example, itcan be seen from FIG. 13 that the fixed ear 60 b is obviously higherthan the fixed ear 60 a, and the fixed ear 60 c is obviously higher thanthe fixed ear 60 b.

A height H1 of the fixed ear 60 c is a distance between a top edge ofthe aortic stent 4 and the top edge of the fixed ear 60 c. In thisembodiment, the height of the fixed ear 60 c is about 7 mm, the heightof the fixed ear 60 b is about 5 mm, the height of the fixed ear 60 a isabout 2.8 mm, and a height H2 of the stent (without the heights of thefixed ears) is about 55 mm.

It needs to be explained that the stent of the artificial valvereplacement device is in a folded state when it is not used, that is, itis a compact tubular structure, and is usually fabricated by machiningtubing made of memory metal material using laser cutting; while it isimplanted into a human body and released, it will expand under theaction of the body temperature and form a loose cylindrical structure.In the present application, if not specially described, all describedstructures of the artificial valve replacement device and the stentthereof refer to the structures having completely expanded in a humanbody.

1-10. (canceled)
 11. A tubular foldable stent, comprising, along alongitudinal direction: a first section; a second section; and a valvesection connected between the first section and the second section, thevalve section being configured for attaching a prosthesis valve therein,wherein the first section has at least one fixed ear provided at one endthereof spaced-apart from the valve section, and each fixed ear isT-shaped and comprises: a neck portion connected to the end of the firstsection; and a head portion; wherein within each fixed ear, the headportion has a width greater than a width of the neck portion in acircumferential direction of the stent, and wherein within each fixedear, the head portion has at least a first curved portion and a secondcurved portion, with a bent portion connecting the first and secondportions, and with the bent portion having a different curvature thanthe curvatures of the first and second portions.
 12. The tubularfoldable stent according to claim 11, wherein each head portion isentirely or partially curved.
 13. The tubular foldable stent accordingto claim 11, wherein within each fixed ear, a ratio of an overall radialthickness of the head portion to a radial thickness of the neck portionis in the range of 1.2 to 3:1.
 14. The tubular foldable stent accordingto claim 11, wherein within each fixed ear, the head portion iswave-shaped in the circumferential direction.
 15. The tubular foldablestent according to claim 11, wherein within each fixed ear, the headportion is positioned symmetrical with respect to the neck portion inthe circumferential direction.
 16. The tubular foldable stent accordingto claim 11, wherein within each fixed each, the head portion isM-shaped or W-shaped.
 17. A tubular foldable stent, comprising, along alongitudinal direction: a first section; a second section; and a valvesection connected between the first section and the second section, thevalve section being configured for attaching a prosthesis valve therein,wherein the first section has at least one fixed ear provided at one endthereof spaced-apart from the valve section, and each fixed ear isT-shaped and comprises: a neck portion connected to the end of the firstsection; and a head portion; wherein within each fixed ear, the headportion has a width greater than a width of the neck portion in acircumferential direction of the stent; and wherein within each fixedear, the head portion is wave-shaped in the circumferential direction.18. The tubular foldable stent according to claim 17, wherein each headportion is entirely or partially curved.
 19. The tubular foldable stentaccording to claim 17, wherein within each fixed ear, a ratio of anoverall radial thickness of the head portion to a radial thickness ofthe neck portion is in the range of 1.2 to 3:1.
 20. The tubular foldablestent according to claim 17, wherein within each fixed ear, the headportion is positioned symmetrical with respect to the neck portion inthe circumferential direction.
 21. The tubular foldable stent accordingto claim 17, wherein within each fixed each, the head portion isM-shaped or W-shaped.
 22. An artificial valve replacement device,comprising: a tubular foldable stent, comprising, along a longitudinaldirection: a first section; a second section; and a valve sectionconnected between the first section and the second section, the valvesection being configured for attaching a prosthesis valve therein,wherein the first section has at least one fixed ear provided at one endthereof spaced-apart from the valve section, and each fixed ear isT-shaped and comprises: a neck portion connected to the end of the firstsection; and a head portion; wherein within each fixed ear, the headportion has a width greater than a width of the neck portion in acircumferential direction of the stent, wherein within each fixed ear,the head portion has at least a first curved portion and a second curvedportion, with a bent portion connecting the first and second portions,and with the bent portion having a different curvature than thecurvatures of the first and second portions; and a prosthesis valvefixed at the valve section of the stent.
 23. The artificial valvereplacement device according to claim 22, wherein each head portion ofthe stent is entirely or partially curved.
 24. The artificial valvereplacement device according to claim 22, wherein within each fixed ear,a ratio of an overall radial thickness of the head portion to a radialthickness of the neck portion is in the range of 1.2 to 3:1.
 25. Theartificial valve replacement device according to claim 22, whereinwithin each fixed ear, the head portion is wave-shaped in thecircumferential direction.
 26. The artificial valve replacement deviceaccording to claim 22, wherein within each fixed ear, the head portionis positioned symmetrical with respect to the neck portion in thecircumferential direction.
 27. The artificial valve replacement deviceaccording to claim 22, wherein within each fixed each, the hear portionis M-shaped or W-shaped.